Composite sheets having a plurality of nonwoven fabrics laminated with an adhesive have been conventionally used in various applications and have been subjected to various types of processing in accordance with the intended uses or purposes. When used in an absorbent article, for example, the composite sheet is formed to improve an appearance and texture of the absorbent article, and to stretch along with body movement and the like.
However, in a case where a composite sheet is used in an absorbent article, the composite sheet is required to stretch along with body movement and the like during putting on or during use, without producing discomfort to a wearer. At the same time, the composite sheet is required to have a strength such that the composite sheet does not break in an extended state is required, while maintaining stretchability.
Japanese Unexamined Patent Application First Publication No. Hei 9-188951 discloses a nonwoven fabric that is obtained by jetting a gas toward and pulverizing a thermoplastic polyurethane elastic body, laminating the pulverized body into a sheet-like shape, and fusion-bonding contact points. However, since the nonwoven fabric thus obtained has a high strength, a material to be coupled therewith to obtain a composite sheet is required to have a high basis weight, thus leading to high cost. In addition, in a case where the nonwoven fabric is used for disposable shorts, a tensile strength thereof is higher than an appropriate tensile strength of disposable shorts. Furthermore, polyurethane elastomer generally has a unique sticky texture and is not preferable to be used in an absorbent article.
In addition, Japanese Unexamined Patent Application First Publication No. 2006-89907 discloses a method for developing extensibility while reducing damage to a sheet by performing stretch processing two times on an elastomer and an extensible fiber composite nonwoven fabric. This method causes fiber breakage and structure breakdown of the sheet in the stretch processing, thus greatly decreasing the strength of the composite sheet.
To obtain a necessary strength, it is required that the composite sheet is made to have a high basis weight or made with an extensible fiber having high fracture elongation, thus leading to high cost. Furthermore, higher basis weight, density and the like may degrade the texture of the sheet. On the other hand, in a case where a nonwoven fabric having a low basis weight is used, a sheet may be broken in a manufacturing process or during use of an absorbent article and the like.